Accessing the graph rest API through Microsoft Azure self-built applications prompts that the mailbox resource account is invalid?

Question

Hello, the version we use VNET, when I create an application on Azure, and authorize the read and write permissions of the calendar and the read permission of the user, and obtain the calendar data of the conference room email account through the graph rest API, the way used by the authentication interface of VNET prompts that this organization cannot be found. However, when using the international version, the authentication is successful, and when you obtain the token and obtain the calendar data of the conference room account again, the return of the meeting room account is invalid. I would like to ask for your help, but I have a problem with what I am doing?

We have AAD, local AD is created and synced to office365, and then authorized are assigned in office365. However, this is limited to general user accounts. Email resource accounts are created directly in the EAC of office365